Decis Deltamethrin Insecticide Decis is a very successful insecticide due to its extraordinary features, such as broad-spectrum, multi-crop, and quick knockdown effect, and excellent awareness in the global agricultural world. Decis is a non-systemic insecticide that acts by contact and ingestion on sucking and chewing insects. Its high lipophilicity provides a high affinity with the insect cuticle.